Access point pictures designated as randomly accessible positions are I pictures or P pictures. Information indicating the decoding sequence (I1, P1, B1, B2, B3, B4, P2, . . . ) of pictures functioning as access points and attribute information (picture_type) indicating whether a picture functions as an access point or is necessary for decoding of the access point following a given access point are recorded on the video information recording medium. Random access is possible even if the GOP interval is lengthened.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A playback method for reproducing video data recorded on a medium, said video data comprising a plurality of video units which each include an intra coded I-picture, a predictive coded P-picture including a group of blocks predicted from one picture and a bidirectionally-predictive coded B-picture including a group of blocks predicted from two pictures, at least one of said video units including an access point P-picture coded by motion compensation prediction using an I-picture located at the beginning of a video unit or a selected preceding P-picture, wherein said P-picture or said B-picture following said access point P-picture is coded without referring to any picture located before said access point P-picture, said medium containing I-picture information including positional information and size information of an access point I-picture which is designated as an access point; said method comprising steps of: identifying a closest access point P-picture preceding a start picture to start playback and said I-picture or said selected preceding P-picture used for coding said access point P-picture; decoding said I-picture or said P-picture used for coding said access point P-picture; decoding said access point P-picture using decoded I-picture or P-picture as a reference picture; and decoding said start picture using decoded access point P-picture as a reference picture, wherein said start picture is decoded without referring to any picture located before said access point P-picture; wherein in the case of accessing said access point I-picture randomly, a location in which said I-picture is stored is identified by reading said I-picture information.
2. A playback apparatus for reproducing video data recorded on a medium, said video data comprising a plurality of video units which each include an intra coded I-picture, a predictive coded P-picture including a group of blocks predicted from one picture and a bidirectionally-predictive coded B-picture including a group of blocks predicted from two pictures, at least one of said video units including an access point P-picture coded by motion compensation prediction using an I-picture located at the beginning of a video unit or a selected preceding P-picture, wherein a P-picture or a B-picture following said access point P-picture is coded without referring to any picture located before said access point P-picture, said medium containing I picture information including positional information and size information of an access point I-picture which is designated as an access point; said playback apparatus comprising: a picture identifying unit for identifying a closest access point P-picture preceding a start picture to start playback or said I-picture or said selected preceding P-picture used for coding said access point P-picture; a first decoder for decoding said I-picture or said P-picture used for coding said access point P-picture; a second decoder for decoding said access point P-picture using decoded I-picture or P-picture as a reference picture; and a third decoder for decoding said start picture using access point P-picture as a reference picture, wherein said start picture is decoded without referring to any picture located before said access point P-picture; wherein in the case of accessing said access point I-picture randomly, a location in which said I-picture is stored is identified by reading said I-picture information.
3. A method for decoding video data comprising a plurality of video units which each include an intra coded I-picture, a predictive coded P-picture including a group of blocks predicted from one picture and a bidirectionally-predictive coded B-picture including a group of blocks predicted from two pictures, at least one of said video units including an access point P-picture coded by motion compensation prediction using an I-picture located at the beginning of a video unit or a selected preceding P-picture, wherein said P-picture or said B-picture following said access point P-picture is coded without referring to any picture located before said access point P-picture, said video data containing I-picture information including positional information and size information of an access point I-picture which is designated as an access point; said method comprising steps of: identifying a closest access point P-picture preceding a start picture to display and said I-picture or said selected preceding P-picture used for coding said access point P-picture; decoding said I-picture or said P-picture used for coding said access point P-picture; decoding said access point P-picture using decoded I-picture or P-picture as a reference picture; and decoding said start picture using decoded access point P-picture as a reference picture, wherein said start picture is decoded without referring to any picture located before said access point P-picture; wherein in the case of accessing said access point I-picture randomly, a location in which said I-picture is stored is identified by reading said I-picture information.
4. A decoder for decoding video data comprising a plurality of video units which each include an intra coded I-picture, a predictive coded P-picture including a group of blocks predicted from one picture and a bidirectionally-predictive coded B-picture including a group of blocks predicted from two pictures, at least one of said video units including an access point P-picture coded by motion compensation prediction using an I-picture located at the beginning of a video unit or a selected preceding P-picture, wherein a P-picture or a B-picture following said access point P-picture is coded without referring to any picture located before said access point P-picture, said video data containing I-picture information including positional information and size information of an access point I-picture which is designated as an access point; said decoder comprising: a picture identifying unit for identifying a closest access point P-picture preceding a start picture to start playback and said I-picture or said selected preceding P-picture used for coding said access point P-picture; a first decoder for decoding said I-picture or said P-picture used for coding said access point P-picture; a second decoder for decoding said access point P-picture using decoded I-picture or P-picture as a reference picture; and a third decoder for decoding said start picture using decoded access point P-picture as a reference picture, wherein said start picture is decoded without referring to any picture located before said access point P-picture; wherein in the case of accessing said access point I-picture randomly, a location in which said I-picture is stored is identified by reading said I-picture information.
5. A playback system comprising: a medium storing video data comprising a plurality of video units which each include an intra coded I-picture, a predictive coded P-picture including a group of blocks predicted from one picture and a bidirectionally-predictive coded B-picture including a group of blocks predicted from two pictures, at least one of said video units including an access point P-picture coded by motion compensation prediction using an I-picture located at the beginning of a video unit or a selected preceding P-picture, wherein a P-picture or a B-picture following said access point P-picture is coded without referring to any picture located before said access point P-picture, said medium containing I-picture information including positional information and size information of an access point I-picture which is designated as an access point; a picture identifying unit for identifying a closest access point P-picture preceding a start picture to start playback and said I-picture or said selected preceding P-picture used for coding said access point P-picture; a first decoder for decoding said I-picture or said P-picture used for coding said access point P-picture; a second decoder for decoding said access point P-picture using decoded I-picture or P-picture as a reference picture; and a third decoder for decoding said start picture using decoded access point P-picture as a reference picture, wherein said start picture is decoded without referring to any picture located before said access point P-picture; wherein in the case of accessing said access point I-picture randomly, a location in which said I-picture is stored is identified by reading said I-picture information.
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October 30, 2007
June 29, 2010
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